The present invention relates to a rotary bearing with a lubricant passage arrangement for supplying a lubricant both to engaging surfaces of a radially inner bearing part and a radially outer bearing part of a rotary bearing, and also to at least one further lubricating point.
The radially inner bearing part and the radially outer bearing part are rotatable relative to one another about an axis of the rotary bearing, and the lubricant passage arrangement includes at least one first lubricant passage with one end which opens into the inner peripheral surface of the radially outer bearing part and another end which is connectable with a lubricant supply, and a second lubricant passage which leads from the outer peripheral surface, of the radially inner bearing part leads to its inner peripheral surface and a ring chamber which is formed between the inner peripheral surface of the outer bearing part and the outer peripheral surface of the inner bearing part, with the first lubricant passage and the at least one second lubricant passage open in the ring chamber. Such a rotary bearing is disclosed for example in German patent document DE 195 19 770 A1.
A threaded spindle of a roller body threaded drive for a machine table is conventionally supported rotatably in a machine bed, and a threaded nut is fixedly connected with the machine table. When the machine table must move with a high speed along the threaded spindle, a correspondingly high rotary speed of the threaded spindle around its axis is required. The spindle rotary speed and thereby also a traveling speed of the machine table are however limited from above by the bending-critical rotary speed of the threaded spindle. For this reason at high machine table-traveling speeds frequently a construction with the fixedly arranged threaded spindle and rotatably arranged threaded unit is selected, as disclosed for example in the German patent document DE 195 19 770 A1.
In the embodiments shown in this patent the radially outer bearing part of the rotary bearing is formed as a special component fixedly connectable with the machine table, and furthermore the thread turns of the threaded nut of the threaded drive are provided on a radially inner peripheral surface of the radially inner bearing part. In other words the radially inner bearing part and the threaded part are formed of one piece with one another. As can be easily seen, for an orderly operation of the threaded drive disclosed in the document DE 195 19 770 A1 both lubrication of engaging surfaces between the radially outer and the radially inner bearing part is required, and also lubrication of the engaging surfaces between the threaded spindle and the threaded nut.
In order to provide the lubrication centrally from a stationary component which performs at least a rotary movement, the embodiments shown in the documents DE 195 19 770 A1 are united through a lubricant passage arrangement with a central lubricating supply point. A first lubricant passage extends from a central lubricant supply point with one end which opens at the inner peripheral surface of the radially outer bearing part in a ring chamber. The ring chamber is arranged between the radially outer and the radially inner bearing part and thereby can supply the engaging surfaces of both bearing parts with lubricant in a simple manner. For supplying the further lubricating point, namely the engaging points between the threaded nut and the threaded spindle, a second lubricant passage is provided which extends through the inner bearing part from its outer peripheral surface to its inner peripheral surface. The lubricant can be supplied from the radially inner end of this second lubricant passage in a simple manner to the engaging surface between the threaded nut and the threaded spindle.
In order to influence the lubricant distribution between the lubrication of the engaging surface of the rotary bearing and lubrication of the engaging surfaces between the threaded spindle and the threaded nut, the document DE 195 19 770 A1 discloses the embodiments shown in FIGS. 10, 11, and 12 with throttle elements at the inner peripheral surface of the radially outer bearing part and/or the outer peripheral surface of the radially inner bearing part. Depending on the properties of the lubricant to be used (lubricant grease or lubricant oil of different viscosity), a differently designed inner and outer bearing parts must be provided. This significantly limits the applications of the individual rotary bearings or individual threaded drives with rotary bearing-supported threaded nut, or a plurality of such a rotary bearings or threaded drives with rotary bearing-supported threaded nuts are needed.